Most DM's assume that gold can be turned freely into magic items. Check with your DM regarding what restrictions he places on buying magic items. I would assume that for a starting character at least, most DMs expect you to buy magic items regardless of how they plan to provide them during the campaign. But then again, always check with your DM.
I do find that if you don't assume gold can be turned freely into magic items, the purpose of gold in 3e becomes somewhat unclear.
In earlier editions, accumulation of wealth meant XP, and after being turned into XP, seemed to mostly serve as the means that higher and higher level characters would eventually be bound to the political life of the game world. Gold was the nest egg that they would use to become landed nobles, with a castle, retainers, and responsibilities. This in turn would open up new styles of play and novel new concerns. 3e play on the other hand seems to contain the assumption that regardless of your level, you'll still be basically living the life of a vagrant adventurer. If the DM doesn't make gold and magic items fungible, it's not so much that the game breaks but that (at least in my experience) players lose interest in gold.